periods and pregnancy

I normally have heavy long periods. They would last up to 9 days. The past two months though they have been farly light and only lasting 3-4 days. I had my period 2 1/2 weeks ago and I am spotting now. It is not a normal period (color and consistency). I am having breast tenderness also. I normally do not get that until my period shows up (which should be in two weeks). Could I possibly be pregnant or could there be another problem.
Thanks
KC